Diagnostic System Check - Vehicle
Diagnostic System Check - Vehicle
1. Before beginning vehicle diagnosis, the following preliminary inspections/tests must be performed:
* Ensure that the battery is fully charged. Refer to Battery Inspection/Test (Battery Inspection/Test).
* Ensure that the battery cables are clean and tight.
* Inspect for any open fuses. Refer to Power Distribution Schematics (Power Distribution Schematics) and Electrical Center Identification Views (Application and ID).
* Ensure that the grounds are clean, tight, and in the correct location. Refer to Ground Distribution Schematics (Ground Distribution Schematics) and Harness Routing Views ([1][2]Harness).
* Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the concern. This would include checking to ensure that all connections/connectors are fully seated and secured.
* Inspect for aftermarket devices that could affect the operation of the system. Refer to Checking Aftermarket Accessories (Checking Aftermarket Accessories).
* Search for applicable service bulletins.
• If the preceding inspections/tests resolve the concern, go to Diagnostic Repair Verification (Verification Tests).
2. Install a scan tool. Verify that the scan tool powers up.
• If the scan tool does not power up, refer to Scan Tool Does Not Power Up (Scan Tool Does Not Power Up).
3. Ignition ON, Engine OFF, verify communication with all of the control modules on the vehicle. Refer to Data Link References (Data Link References) for information on the modules you should expect to communicate.
• If the scan tool does not communicate with one or more of the expected control modules, refer to Data Link References (Data Link References).
Important: Open the drivers door to ensure retained accessory power mode (RAP) is inactive during this test. The engine may start during this test. Turn the engine OFF as soon as the crank power mode has been observed.
4. Access the Power Mode parameter on the scan tool. Verify the power mode parameter matches all the ignition switch positions. Refer to Power Mode Description and Operation (Power Mode Description and Operation) for information on the power mode states that correspond to each ignition switch position.
• If the power mode parameter does not match the ignition switch position for all ignition switch positions, refer to Power Mode Mismatch (Power Mode Mismatch).
5. Attempt to start the engine. Verify that the engine cranks.
• If the engine does not crank, refer to Symptoms - Engine Electrical (Symptoms - Engine Electrical).
6. Attempt to start the engine. Verify the engine starts and idles.
• If the engine does not start and idle, refer to Engine Cranks but Does Not Run (Engine Cranks But Does Not Run) for the 4.2L engine or Engine Cranks but Does Not Run (Engine Cranks But Does Not Run) for the 5.3L or 6.0L engine.
Important: Do not clear any DTCs unless instructed to do so by a diagnostic procedure.
Important: If any DTCs are Powertrain related DTCs, select Capture Info in order to store the DTC information with the scan tool.
7. Use the appropriate scan tool selections to obtain DTCs from each of the vehicle modules. Verify there are no DTCs reported from any module.
• If any DTCs are present, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) and diagnose any current DTCs in the following order:
1. DTCs that begin with a U.
2. Any of the following: B1000, B1001, B1004, B1007, B1009, B1017, C0240, C0550, P0601, P0602, P0603, P0604, P0606, P0607, P060D, P060E, P062F, P1516, P1621, P2101, or P2610.
3. Any of the following: B1372, B1375, P0562, or P0563.
4. Component level DTCs.
5. System level DTCs.
6. Any remaining DTCs.
8. If the customer concern is related to inspection/maintenance (I/M) testing, refer to Inspection/Maintenance (I/M) System Check (Inspection/Maintenance (I/M) System Check) for the 4.2L engine or Inspection/Maintenance (I/M) System Check (Inspection/Maintenance (I/M) System Check) for the 5.3L or 6.0L engines.
• If none of the previous tests or inspections addresses the concern, refer to Symptoms - Vehicle (Symptoms - Vehicle).